1. Field of the Invention
The present invention relates to a nonreciprocal circuit device, such as an isolator and a circulator, for use in a high-frequency band such as a microwave band; a communication apparatus using the nonreciprocal circuit device; and a manufacturing method for the nonreciprocal circuit device.
2. Description of the Related Art
Conventionally, apparatuses such as communication apparatuses use nonreciprocal circuit devices, such as lumped-parameter-type isolators and circulators, making use of their characteristics in which the amount of attenuation is extremely small in the direction along which a signal is transmitted, and is extremely large in the reverse direction.
An exploded perspective view of a conventional isolator is shown in FIG. 21A, and an interior construction thereof is shown in FIG. 22B. However, an Axe2x80x94A cross-sectional view in FIG. 22B shows only a cut face along the Axe2x80x94A line.
As shown in FIGS. 21A to 22B, the isolator is constructed such that a magnetic assembly 5 having central conductors 51, 52, and 53 and a ferrite member 54, a permanent magnet 3, and a resin housing 7 are individually arranged in a closed magnetic circuit formed primarily by an upper yoke 2 and a lower yoke 8. Ports P1 and P2 of the central conductors 51 and 52 are connected to input/output terminals 71 and 72 formed in the resin housing 7 and to matching capacitors C1 and C2. A port P3 of the central conductor 53 is connected to a matching capacitor C3 and a termination resistor R. One end of each the capacitors C1, C2, and C3 and the termination resistor R is connected to a ground terminal 73.
As shown in FIGS. 22A and 22B, one electrode of the resistor R is connected to the ground terminal 73, the other electrode is connected to an electrode provided in the resin housing 7. Also, the port P3 of the central conductor 53 is connected to the electrode and an upper electrode of the matching capacitor C3 so as to stride across the two electrodes.
FIGS. 23A and 23B show an upper view and a cross-sectional view, respectively, of an isolator having a construction differing from that shown in FIGS. 22A and 22B. Specifically, the construction in FIGS. 23A and 23B is in a state that the upper yoke 2 is removed from that shown in FIGS. 22A and 22B. In this example, one electrode of the termination resistor R is connected to the ground terminals 73, the other electrode is connected to the upper electrode of the matching capacitor C3, and the termination resistor R is thereby arranged in a position higher than the matching capacitor C3.
In the conventional isolator having the construction shown in FIGS. 22A and 22B, since the termination resistor R and the matching capacitor C3 are arranged at the same height, the dimensions of the matching capacitor C3 are restricted by the termination resistor R. Specifically, the inside-diametric dimension of the resin housing 7 cannot be reduced smaller than the sum of the addition of longitudinal dimensions of the termination resistor R and the matching capacitor C3. Therefore, the isolator is not suitable to miniaturization.
In the conventional isolator having the construction shown in FIGS. 23A and 23B, since the termination resistor R is arranged higher than the matching capacitor C3, the dimensions of the matching capacitor C3 are not restricted by the termination resistor R. Therefore, the isolator can be miniaturized smaller than that having the construction shown in FIGS. 22A and 22B. However, in the manufacture of the isolator shown in FIGS. 23A and 23B, a solder paste is applied on a bottom face (grounded face). Therefore, the matching capacitor C3 tends to skew when a binder component melts and volatilizes, and solder powders melt. Thereafter, when a solder paste on the bottom face of the matching capacitor C3 becomes in a uniformly melted state, the skewed matching capacitor C3 returns to the original state. However, at an initial stage when the matching capacitor C3 is skewed because of heating of the solder paste, the termination resistor R is also caused to skew. In addition, a lower face of the termination resistor R individually contacts the immovable ground terminal 73 and the matching capacitor C3 that tends to skew. Therefore, when the solder melts, a so-called tombstone phenomenon is apt to occur. Specifically, chip-type components are apt to rise according to a surface tension of the melted solder, and insufficient contact is apt to be caused.
Accordingly, an object of the present invention is to provide a nonreciprocal circuit device that solves the above-described problems, that can be easily miniaturized, and that improves reliability.
Another object of the invention is to provide a communication apparatus using the nonreciprocal circuit device.
Still another object of the invention is to provide a manufacturing method for the nonreciprocal circuit device.
According to one aspect of the present invention, a nonreciprocal circuit device of the present invention is configured such that a magnetic body which receives a direct-current magnetic field and a plurality of central conductors intersecting with each other provided on the magnetic body are stored in a housing. A substrate having a high-frequency component is stored in the housing, and at least one port of the plurality of central conductors is electrically connected to one of an electrode of the high-frequency component and an electrode on the substrate which is electrically connected to the electrode of the high-frequency component.
In the above construction, the high-frequency component, such as a resistor, is premounted on the substrate, thereby solving the above-described problems that are caused when the substrate is overlaid on the matching capacitors and the like. According to the above, a highly reliable nonreciprocal circuit device can be obtained in which the high-frequency component, such as a resistor, an inductor, or a capacitor, does not cause insufficient connection due to, for example, a tombstone phenomenon, in a housing.
In the nonreciprocal circuit device, a cutout portion may be formed at one of a side and a corner of the substrate. According to the cutout portion, when the substrate is stored in the housing for the nonreciprocal circuit device, an arrangement can be made such that a machine for performing the storing processing automatically detects the obverse and reverse faces and the direction of the substrate.
In addition, in the nonreciprocal circuit device, electrodes on obverse and reverse faces may be electrically connected together via an end face of the cutout portion. According to this, the cutout portion is concurrently used as the through-hole.
Furthermore, the high-frequency component includes electrodes on plate-like obverse and reverse faces thereof, the arrangement may be such that the electrode on the reverse face of the high-frequency component is electrically connected to the electrode on the substrate, and the electrode on the obverse face of the high-frequency component and the electrode on the substrate are connected together via a step-shaped metal plate. According to this arrangement, the high-frequency component having the electrodes on plate-like obverse and reverse faces of its own can be mounted on the substrate, and further miniaturization can be implemented overall by suing the small high-frequency component.
For the high-frequency component, one of a resistor, an inductor, and a capacitor may be used. For example, on the substrate, an inductor and a capacitor for forming a filter circuit may be mounted, or an inductor as part of a filter circuit may be mounted. Thus, a nonreciprocal circuit device having a resistor as a termination resistor and a nonreciprocal circuit device having a filter circuit formed of an inductor and a capacitor can be easily configured.
According to another aspect of the present invention, a communication apparatus is configured using the above-described nonreciprocal circuit device in a transmission/reception circuit section of an antenna-sharing circuit. This allows the communication apparatus to be miniaturized.
According to still another aspect of the present invention, a manufacturing method for the nonreciprocal circuit device comprises steps of mounting high-frequency components in units of a plurality of sections of a primary substrate; cutting out substrates from the primary substrate in the units of the plurality of sections; and storing, in the housing, a respective one of the substrates on which the high-frequency components are mounted, the magnetic body which receives the direct-current magnetic field, and the plurality of central conductors intersecting with each other provided on the magnetic body. According to this manufacturing method, since mounting of the high-frequency components on the primary substrate and forming of the plurality of substrates can be performed on the block, the productivity can be improved.
According to still another aspect of the the present invention, a manufacturing method for the nonreciprocal circuit device comprises steps of cutting out individual substrates from a primary substrate in teh units of a plurality of sections, mounting high-frequency components on the individual substrate, and storing, in the housing, each of the substrates, the magnetic body which receives the direct-current magnetic field, and the plurality of central conductors intersecting with each other provided on the magnetic body. According to the above, the invention can be applied to a manufacturing system for individually mounting a high-frequency component on the substrate.
According to still another aspect of the present invention, a manufacturing method for the nonreciprocal circuit device comprises steps of providing openings at a border of a plurality of sections of a primary substrate, forming cutout portions by cutting substrates from the primary substrate in the units of the plurality of sections. According to the above, the cutout portions are formed on the block, the productivity is thereby improved.
Furthermore, according to still another aspect of the present invention, a manufacturing method for the nonreciprocal circuit device comprises steps of detecting obverse and reverse faces and the direction of said substrate having cutout portions according to the position of said cutout portions, storing the substrate in the housing such that a predetermined face of the substrate is arranged in a predetermined direction. With this arrangement, the substrate can be securely stored in the housing for the nonreciprocal circuit device, without causing misplacement in the obverse and reverse sides and the direction of the substrate.